Electrical clamp having scraper contact



Jan. 9, 1968 D. c. HUBBARD ETAL 3,

ELECTRICAL CLAMP HAVING SCRAPER CONTACT Filed July 15, 1965 0 INVENTORS.3 David C. Hubbard James Thomas Odom United States Patent 3,363,219ELECTRICAL CLAMP HAVING SCRAPER CONTACT David C. Hubbard and JamesThomas Odom, Centralia, Mo., assignors to A. B. Chance Company,Centralia, Mo., a corporation of Missouri Filed July 15, 1965, Ser. No.472,260 3 Claims. (Cl. 33995) This invention relates to a safety groundclamp particularly adapted for use in connecting high voltage electricallines to a grounded supporting tower during maintenance and repairoperations.

In order to provide for the safety of linemen during repair of highvoltage transmission lines, it is the practice to ground the lines underrepair to the metal tower which supports the lines in spacedrelationship to the ground. This is to preclude the possibility ofinjury to linemen should the lines be inadvertently re-energized beforethe repair operation has been completed.

The customary procedure is for the lineman to electrically connect thelines under repair to the body of a clamp which is, in turn, secured toone of the structural members of the supporting tower. Because of theextremely high currents involved should re-energization occur, it isrequisite that the contact between the clamp and the tower memberpresent negligible resistance to the flow of electric current.Otherwise, disintegration of the clamp would occur at the point ofcontact with the tower member, resulting in interruption of the currentpath to ground which, of course, would present an extremently hazardouscondition to personnel.

Since the surfaces of the structural members of supporting towers arefrequently coated with oxides and other contaminants which preclude theestablishment of a low resistance electrical connection, such coatingsmust be removed to eliminate the hazard of high resistance groundconnections.

It is, therefore, the primary object of this invention to provide anelectrical connector having a surface abrading contact face which ismovable during installation of the connector to remove oxides andcontaminants on the surface to be gripped by the connector, therebyproviding a low resistance electrical connection.

Another object of this invention is to provide an electrical connectoras aforesaid wherein the current path from the line to the contact faceis achieved by a direct mechanical connection without the use of movablecontact faces.

Still another object of the instant invention is to provide a connectoras set forth above having resilient pressure-applying means whichmaintains sustained contact pressure in the event of movement of theconnector during electrical stress, normal pressure relaxation, or minormelting of the scrubbing points by current flow therethrough.

A further object of the invention is to provide a connector as aforesaidhaving a handle rigidly coupled with the contact face to impart thescrubbing action thereto, which handle also serves as a terminal forconnecting an electrical line to the connector.

Other objects will become apparent as the detailed description proceeds.

In the drawing:

FIGURE 1 is an elevational view of the connector clamp illustrating thesame in clamping engagement with an angle member of a support tower;

FIG. 2 is a bottom view of the connector;

FIG. 3 is an enlarged, detailed view of the scrubber face taken alongline 33 of FIG. 1; and

FIG. 4 is a vertical sectional view taken along line 4-4 of FIG. 3.

ICC

The numeral 10 designates a C-shaped body having a pair of spaced-apartlegs 12 and 14. Leg 12 is somewhat shorter in length than leg 14 andthreadably receives a pressure member 16 in the form of a screw 17provided with a T-shaped handgrip 18. Leg 14 has a transverse opening 20therethrough (FIG. 4) in axial alignment with pressure member 16.Opening 20 receives a rotatable anvil 22 having a cylindrical shank 24terminating in a head 26.

Head 26 is provided with two sets of concentric, arcuate ridges 28 and30, each set of ridges comprising four arcuate segments separated bynotches 32. It will be appreciated in FIG. 4 that the ridges 28 and 30are toothed-shape and present cutters, the cutting action of the ridgesbeing enhanced by the presence of the notches 32.

A pair of opposed compression washers 34 are disposed between head 26and the inner surface 36 of leg 14. The end of shank 24 remote from head26 has a transverse aperture 38 therein which receives a pin 40extending through a split clamp 42. A drawbolt 44 maintains the splitclamp rigid with shank 24, pin 40 serving to positively precluderotation of clamp 42 relative to shank 24. The split clamp forms one endof a handle 46 which extends away from the clamp at approximately a 45angle as illustrated.

The central portion of handle 46 comprises an internally threadedenlargement 48 which receives the threaded end of a cable ferrule 50, apin 52 being utilized to rigidly interconnect the end of the ferrule andthe enlargement. Ferrule is utilized to connect the free end of handle46 to an electrically conductive cable 54 which, in a typicalapplication of the instant invention, is utilized as a lead toelectrically connect the handle to a high voltage transmission line.

An angle retainer 56 is secured to the end of leg 14 by a thumbscrew 58,retainer 56 being illustrated in engagement with an angle member 60which represents a structural member of a high voltage transmission linesupport tower. The connector is secured to the angle member by advancingthe rotatable screw 17 toward the contact face presented by ridges 28and 30 to clamp the member between screw 17 and head 26.

In use, handgrip 1-8 is rotated to advance screw 17 until the anglemember 60 is clamped between the screw and the contact face of head 26with suflicient force to fn'ctionally engage the ridges 28 and 30 withthe surface of the angle member. Handle 46 is then gripped by theoperator and manipulated as illustrated in FIG. 2 to rotate shank 24about its longitudinal axis. Preferably, a back and forth swingingmotion is imparted to handle 46 to effect a scrubbing or scraping actionat the surface of the angle member in engagement with the scrubbercontact face.

It will be appreciated that the notches 32 in the scrubber face assistin providing a cutting action since the notches divide ridges 28 and 30into cutter segments to more effectively abrade the surface of the anglemember. Thus, surface oxides or other contaminants are removed from themember so that the crown of each of the cutting ridges ultimatelycontacts a clean surface and provides a low resistance electricalconnection between shank 24 and the angle member. Although the scrubberface configuration shown is generally preferred, it should be understoodthat other face configurations could also be employed to produce asatisfactory cleaning action.

After the handle is rotated to scrub the surface of the angle member,handgrip 18 is further advanced until maximum clamping action isobtained and the connector assembly is firmly attached to the anglemember such that relative movement of the connector and the member isdifficult. Retainer 56 may be utilized to further establish a rigidjoining of the connector to the member.

As handgrip 18 is rotated to its maximum pressure poa the utilization ofthe instant invention since sustained contact pressure is provided tomaintain'the low resistance electrical connection should relativemovement of the connector and the angle member occur during electricalstress, normal pressure relaxation, or minor melting of the crowns ofthe cutter segments by current flow there through. In this manner, thecompressed washers provide an additional margin of safety which, ofcourse, is vital in the utilization of the instant invention as a meansof preventing injury to linemen in the event of inadvertentre-energization of transmission lines during repair and maintenanceoperations. 7

It should also be noted that the contact path provided by the inventionfrom the scrubber face to cable 54 comprises a unitary, electricallyconductive structure after .assembly of the components of handle 46 andjoining of the handle with shank 24. Therefore, electrical continuity isestablished via a direct mechanical connection without the use ofmovable contact faces which would create additional problems of surfacecontamination and high resistance points.

Having thus described the invention, what is claimed as new and desiredto be secured by Letters Patent is:

1. An electrical connector comprising:

a body having a pair of spaced legs;

an electrically conductive anvil rotatably carried by one of said legs;

pressure means carried by the other of said legs and movable toward theanvil for clamping a conductive component between the pressure means andthe anvil;

an electrically conductive handle rigid with said anvil and extendingtherefrom for rotating the anvil,

said handle being provided with means for coupling the handle with acurrent-carrying line; and

means on the anvil for scrubbing said component when the latter is heldbetween the pressure means and the anvil and upon rotation of the anvilby the handle, whereby to provide a low resistance electrical connectionwith said component by removal of surface oxides or other contaminants.

2. An electrical connector comprising:

a body having a pair of spaced legs;

an electrically conductive anvil rotatably carried by one of said legsand having a shank terminating in a head;

pressure means carried by the other leg for movement toward and awayfrom the anvil,

said one leg having a transverse opening therein aligned with saidpressure means and receiving said shank with said head disposed infacing relationship to the pressure means;

a resilient, compressible element between said one leg and said head andbiasing the latter toward said pressure means;

an electrically conductive handle rigid with said shank and extendingtransversely therefrom for rotatingrthe anvil, a

said handle being provided with means for coupling, the

handle with a current-carrying line; and

means on said head for scrubbing a conductive component held between thepressure means and the head during rotation of the latter by saidhandle, whereby to provide a low resistance electrical connection withsaid component by removal of surface oxides or other contaminants and toprovide sustained contact pressure by compression of said element-upontightening of said pressure means.

3. The invention of claim 2: V

and a retainer secured to the free end of said one leg for engaging saidconductive component to assist in preventing relative movement of thebody'and the conductive component when the latter is held between thepressure means and the head, said scrubbing means comprising a pluralityof spaced,

arcuate ridges on said head disposed in a circular pattern coaxial withsaid shank.

References Cited I UNITED STATES PATENTS 1,810,901 6/1931 Bormann et a1;24-263.3 1,833,462 11/1931 Hagist 15137 f 2,420,895 11/ 1947 Merriman339264 2,431,439 a 11/ 1947 Williams 339-264 2,659,954 11/1953 Woolsey24--279 FOREIGN PATENTS 1,102,843 3/ 1961 Germany.

MARVIN A. CHAMPION, Primary Examiner.

I EDWARD c. ALLEN, Examiner.

1. AN ELECTRICAL CONNECTOR COMPRISING: A BODY HAVING A PAIR OF SPACEDLEGS; AN ELECTRICALLY CONDUCTIVE ANVIL ROTATABLY CARRIED BY ONE OF SAIDLEGS; PRESSURE MEANS CARRIED BY THE OTHER OF SAID LEGS AND MOVABLETOWARD THE ANVIL FOR CLAMPING A CONDUCTIVE COMPONENT BETWEEN THEPRESSURE MEANS AND THE ANVIL; AN ELECTRICALLY CONDUCTIVE HANDLE RIGIDWITH SAID ANVIL AND EXTENDING THEREFROM FOR ROTATING THE ANVIL, SAIDHANDLE BEING PROVIDED WITH MEANS FOR COUPLING THE HANDLE WITH ACURRENT-CARRYING LINE; AND MEANS ON THE ANVIL FOR SCRUBBING SAIDCOMPONENT WHEN THE LATTER IS HELD BETWEEN THE PRESSURE MEANS AND THEANVIL AND UPON ROTATION OF THE ANVIL BY THE HANDLE, WHEREBY TO PROVIDE ALOW RESISTANCE ELECTRICAL CONNECTION WITH SAID COMPONENT BY REMOVAL OFSURFACE OXIDES OR OTHER CONTAMINANTS.